Why Use Organic Matter in the Garden? Improve Fertility!

Picture of cupped hands holding wood chips

Ask any keen gardener you know about using organic matter on their plot, and they will be sure to tell you all about the fantastic results they have had with it.

Adding organic matter to your garden adds vital nutrients to the soil. It also feeds the microorganisms that are crucial in maintaining the structure of the soil. As a result, the fertility of your soil is greatly improved.

From flowers to fruit and veg, all plants benefit from growing in soil rich in organic matter.

So, what’s the secret of this amazing stuff, and why should you use it in your garden? Read on to find out.

What is Soil Fertility?

The fertility of your garden’s soil is its ability to provide an ideal habitat that plants can thrive in.

To achieve this, the soil should be rich in essential plant nutrients, and both retain and drain moisture in just the right amounts to give your plants what they need. One of the key indicators of the level of fertility your soil has is the soil structure.

As a general rule of thumb, pale soil that either dries out rapidly or doesn’t dry out at all is likely to be quite infertile.

Dark, rich, moist, crumbly soil that smells like a walk through a wet forest is showing all the signs of being highly fertile!

But not all garden soils are created equal, and you may have noticed tell-tale signs that yours is less than fully fertile.

Never fear, though! The addition of some well-chosen organic matter can work wonders to improve the structure, boost fertility and give your soil the oomph it needs to let your plants flourish.

Essentially, all life depends upon the soil… There can be no life without soil and no soil without life; they have evolved together.

Dr. Charles E Kellogg

What is Organic Matter for the Garden?

First things first, what is this amazing stuff that will transform your soil?

In simple terms, organic matter in gardening refers to once-living materials added to the soil to improve its quality.

Organic matter is sometimes referred to as ‘soil improver’ or ‘soil conditioner,’ and many materials can be used.

Using organic matter in your garden goes way beyond just compost!

What are the Best Types of Organic Matter to Use in My Garden?

Some examples of organic matter that you may have heard of include:

  • Fallen leaves: These are most beneficial after being composted or turned to leaf mulch.
  • Homemade compost: made from suitable kitchen and garden waste.
  • Municipal compost: This is often available through local authorities. It’s composted in larger heaps than most home composts, so the temperatures are higher and there are less likely to be weeds in the compost.
  • Animal manure: This can be used either rotted down or fresh, depending on your purposes and is often available for sale (or free if you’re lucky) from local farmers and stables. You’ll get the best results using manure for nitrogen loving plants like potatoes, corn, or even your lawn.
  • Bark chips: These are best used as a mulch on the surface of your soil, to suppress weed growth and keep moisture and nutrients in. They’re not suitable for mixing in, as wood that hasn’t been broken down can actually deplete the nitrogen levels in soil. As a mulch though, they are one of my favorite materials. They look decorative and also smell lovely!
  • Straw: This is another fantastic natural mulch that you can use to prevent weed growth as well as aiding moisture retention. It can also be used as a protective layer for more delicate plants as they lay dormant over the winter.
  • Cover crops: This is an example of organic matter benefiting your garden whilst growing. Cover crops include things like Alfalfa, Buckwheat and Rye, and they work as a literal cover for your soil. They can help you control soil erosion, moisture retention and weed suppression whilst encouraging wildlife in your garden.

I have a video about proven cover crops. You can watch it below.

How Does Adding Organic Matter Improve Fertility?

In wild places, plants naturally spring up in the most fertile soils and, therefore, the easiest to establish themselves.

The rich ‘black gold’ that you will see in very fertile soil is the end product of plenty of decomposed organic matter. It’s known as hummus, and although it’s not the tasty kind humans eat, plants find it just as delicious!

This super-fertile soil is created by the nitrogen cycle, which is straightforward terms, operates like this:

  • Plant and animal wastes decompose, adding nitrogen to the soil.
  • Bacteria in the soil convert those forms of nitrogen into forms plants can use.
  • Plants use the nitrogen in the soil to grow.
  • People and animals eat the plants; then animal and plant residues return nitrogen to the soil again, completing the cycle.

We are trying to replicate the nitrogen cycle when we use organic matter in our gardens because most domestic gardens are artificially created, we must add the organic matter needed to create fertile soil.

How to Use Organic Matter in Your Garden

We’ve already discussed some of the materials you can use as organic matter in your garden, but they are not all applied in the same way. Here are some of the different ways I like to put the organic matter to work:

As a Mulch

Mulch is super beneficial for your soil’s fertility. It is basically a layer of material added to the surface. Mulch acts like a lovely blanket that protects the soil from getting dried out by the sun and blown away by the wind when applied properly.

Mulch also makes it much harder for weeds to breakthrough as well as locking in moisture. In the long term, this will make life much easier for you. I’m sure you’ll agree that the less weeding and watering you need to do, the better!

Although non-organic matter mulches are available, they are not nearly as beneficial. When you use nutrient-rich organic matter, the soil gets the added benefit of absorbing these nutrients as the mulch begins to break down. This process mimics the all-important nitrogen cycle that I mentioned earlier.

I have a video about proven garden mulch ideas. You can do that below.

As a Fertilizer

Adding fertilizer is a great way to target the specific nutritional needs of your soil. Some plants may enjoy nitrogen-rich growing conditions, while others thrive on higher potassium levels like tomatoes and flowering plants.

Fertilizer delivers the required nutrients to your plants in the most readily available form.

You will no doubt have seen plenty of chemical fertilizers available for sale on the shelves of your local garden center. Whilst these are crafted to combine the ideal levels of certain nutrients for plants, they often do not benefit the structure of the soil itself.

Organic matter as a fertilizer not only provides the nutrients that plants need, it is also fantastic for improving the soil structure. Soil rich in organic matter retains moisture and nutrients for longer, and as a result, the soil’s long-term fertility is ensured.

Of course, different types of organic matter contain different levels of nutrients, and you’ll want to be sure that you’re applying the right stuff to get the maximum benefits for your soil.

The best way to do this is to carry out a soil test.

Once you know what your soil lacks, you can choose the best organic materials to give it the boost it needs.

Nutrient DeficiencyOrganic Matter to Use
NitrogenPoultry Manure (pelleted form makes the nitrogen most readily available)
PhosphorusBone Meal
MagnesiumEpsom Salts (yes, the ones you can bathe in!)
As you can see, most nutrient deficiencies in the soil can be remedied through organic matter.


Making your own compost out of organic material from your kitchen and garden is really satisfying. The knowledge that you’re creating something so beneficial to your soil and plants can be a huge boost to your confidence as a gardener.

The key to getting the most from all that lovely compost you’ve nurtured is to make sure it’s properly rotted down before you use it.

As I mentioned earlier in the post, things like wood chippings and cuttings can deplete the soil’s nitrogen if they’re not well rotted.

The minimum time it takes for compost to be useable is around six months, but it can take as long as two years to reach its best.  You’ll know that it’s just right when the color is dark brown, the texture crumbly, and the smell like wet autumn leaves.

The best time of year to dig compost into your soil is spring before most plant growth has picked up speed.

It may seem like a lot of work to make compost yourself, but trust me, it’s worth it!

I have a video about why you should make compost at home. Watch it below.

As a Compost Activator

Some compost heaps are stubborn! You may find that yours is taking a long time to get to the ideal consistency, or maybe it just doesn’t seem to be getting started at all!

In most cases, the ingredient that is lacking is sufficient nitrogen. This is where compost activators come in handy. These clever substances stimulate the composting process to help start or speed up decomposition.

You can use organic matter in this way too. Here are a few materials I’d recommend to give your sluggish compost heap the shot of nitrogen it needs to get moving

Green Plants

Comfrey, clover, alfalfa, and other green plants, are all high in readily available nitrogen. They benefit the soil when they are growing and also make excellent compost activators.

Picture of clover


Picture of soil with manure

Certain types of well-rotted manure can work well to boost your nitrogen content and kick-start composting. Take care when adding it, though. Fresh manure can burn plant roots, so a mature option is always best. Use the manure as a green, nitrogen-rich layer in your compost system, and be sure to sandwich it between two brown, carbon-rich layers to get the best results.

Coffee grounds

Most of us crave that first caffeine hit of the morning, but it may not have occurred to you that it could give your soil a boost, too! Coffee grounds contain a reasonable amount of nitrogen and are a worthwhile addition to your compost heap or bin.

Picture of spooning coffee grounds around a plant pot
Don’t toss your coffee grounds in the trash! Your compost heap will thank you for the nitrogen boost.

Conclusion on why use organic matter in the garden

The higher the level of well broken-down organic matter in the soil, the more fertile that soil becomes. So, your plants get the full benefit of all the moisture and nutrients that lovely hummus provides.

As we have seen, there are loads of different ways to incorporate organic matter into your garden and many materials you can use. The best part is that many of them are free and already in your home or garden so that you can get stuck in right away!

I hope this post has given you an idea of how beneficial the use of organic matter in your garden is to your soil’s fertility.

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Tony O'Neill

I am Tony O'Neill, A full-time firefighter, and professional gardener. I have spent most of my life gardening. From the age of 7 until the present day at 46. My goal is to use my love and knowledge of gardening to support you and to simplify the gardening process so you are more productive

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